Figure 3. Western blot analysis of H3K27m3 levels in histones extracted from young and old kidneys. Upper panel, equal amounts of acid-extracted proteins from nuclear-enriched tissue fraction were subjected to SDS PAGE in 13% gels, transferred to PVDF membranes and stained with anti-H3K27m3 antibodies. Representative parts of ponseau-stained membranes are also shown (Load). Lower panel, results of densitometry analysis of bands shown in the upper panel. Y, young (4mo), O, old (28mo for F344, 32mo for FBN-F1). Signal intensities were normalized to load. Shown are mean values +SD, **p<0.005.